The Endocrine System


Uploaded by bozemanbiology on 17.03.2012

Transcript:



Hi. It's Mr. Andersen and welcome to the Endocrine System podcast. If you look
way up there at that guy, his name is Robert Wadlow and that guy, I have not idea what
his name is because he's not Robert Wadlow. Robert Wadlow is the tallest man that we have
in modern day. He was something like 8 feet 11.5 inches at the time of his death and he
was that tall because he was a pituitary giant. In other words, he had a tumor, we now know,
that was pushing on his pituitary. It was making it produce a hormone called growth
hormone which made him get as tall as he eventually was. And so that wasn't normal. It does put
pressure, and he died young just mostly I think due to circulation problems. He started
to get blood clots. And so basically it talks a little bit about the endocrine system. When
I'm talking about the endocrine system, the other system that's really important to talk
about is called the nervous system. So the nervous system remember is basically going
to be made up of neurons. So you have all these dendrites that come into the cell bodies.
So the cell body looks like this and then you have an axon that comes way down here
and then you're going to have another neuron down here that's connected with a bunch of
dendrites to a cell body and it's going to move here. Now this distance right here, or
excuse me, the separation between the two is called a synapsis. A synapsis is going
to be a gap between neuron 1 and neuron 2. Now why is the synapse important? Well, we
get control over the chemicals that we send. But this podcast isn't about the nervous system
and the reason why is that nerves just travel in one direction, from this neuron to another
neuron onto another neuron. They just go in one direction. And so my analogy is it's like
Gmail. When you send an email from one person to another person or they send it from one
person to another person, that's like the nervous system. You're sending a message from
one person with a clear destination and that's the nervous system. It goes really fast and
it's going to target a specific cell. And so when do we use the nervous system? When
he have to do something really quick. So if somebody were to throw something at me and
I were to dodge it, that would be my nervous system that is acting. So the endocrine system
is more like Facebook. If I were to post to my Facebook status update that I am working
on a cell communication podcast by myself. Ironic. And I just put it out there, there's
going to be a delay. There's going to be time before other people look at it and dislike
it or like it or respond to it. And so that's going to be more like the endocrine system.
I'm sending it out to everybody and whoever wants to respond to it can. And so basically
keep that in the back of your mind. What are some terms that you should understand? First
of all anything that is going to send out these messages in the endocrine system is
called a gland. And we'll go over ten important glands. The chemical that they send out is
called a hormone. And then it's going to target cells or not. It may target certain cells
or it may not target other cells. And so we could send for example follicular stimulating
hormone from the pituitary. It's only going to effect the ovaries and the testes, but
if we send out growth hormone that's going to effect all the cells in your body. So what
do those hormones do? They simply diffuse throughout your body. They're going to spread
throughout your body. And so they are going to bump into cells or not. They're going to
spread throughout your whole body and that's why if you've ever felt like adrenaline, you
almost get in a car accident, you just feel like almost something coursing through your
body, that's going to be your endocrine system. Now when they find cells one of two things
can happen. If they are a water soluble hormone, an example could be epinephrine or adrenaline,
they're water soluble, basically what they're going to do is they're going to dock with
a protein on the surface of their cell. Since they're water soluble they can't gain entry
to the cell. And so usually what they'll do is they'll set up some kind of signal transduction
pathway to have some kind of an action out here or have another action inside the nucleus
where we could make certain specific genes or certain proteins, transcribe certain genes.
But that would be water soluble. We also have what are called lipid soluble. Testosterone's
an example of that. Basically since it's lipid soluble it's going to move right through that
lipid by layer that is the cell membrane and it also can target with the cell and move
right into the nucleus, because again there's going to be a lipid by layer here as well.
And so lipid soluble hormones are going to move all the way into the cell. Water soluble
are just going to dock with the receptor protein on the surface. And so here's our endocrine
system. The endocrine system is not as tightly linked together like the circulatory system,
but again it doesn't have to be because it's sending hormones through out the whole body.
And so basically we've got glands going all the way up to the top from the pineal gland
all the way down to the ovaries and testes on the bottom. And so basically what I want
to do is I've chose ten glands in the endocrine system, ten that I think are pretty important.
There are more than that. And then I've just chosen one hormone for each of these and we're
going to talk about that. So let's talk, let's start at the top. The first one is going to
be the pineal gland. The pineal gland is right here. Basically what the pineal gland is going
to secrete is a chemical called melatonin. It does that only when it's night time. And
so if your eyes are open during the day you're not going to be secreting melatonin. But when
you close your eyes at night, it's going to start giving off melatonin. And so basically
what that does is that it allows our brain to tell what time of the day it is and it
also allows us to figure out what season it is. And so basically we can set up what's
called our circadian rhythm. So it's basically our internal clock and it's pineal gland doing
that. Next let's move down here. This part of our brain is actually called the hypothalamus.
And the hypothalamus is kind of the connection between the brain and the endocrine system.
And so it can secrete hormones as well, but we're going to say it's influencing the pituitary.
We're going to talk about what the pituitary does. Pituitary basically, if we were to look
at it like this, the pituitary let me blow that up a little bit, so the pituitary is
going to go down like this and so it's going to have two lobes to it. It's going to have
the anterior, anterior means towards the front or towards the head, and then it's going to
have the posterior. Posterior is going to be towards your rear end is the best way to
think about it. And so what is the anterior pituitary give off? Well it gives off growth
hormone. It gives off a number of other things, it gives off endorphins, it gives off follicular
stimulating, it gives off all these different hormones, but one that we're going to talk
about is growth hormone. What's growth hormone going to do? Growth hormone again is going
to float throughout the rest of your body. It can do that in the circulatory system or
through the interstitial fluid and basically it's going to cause the cells to grow. So
they're going to get bigger. If we talk about the next one, anterior, or excuse me, posterior
pituitary, it gives off oxytocin but the one important hormone we are going to talk about
is anti-diuretic hormone or ADH. And so anti-diuretic hormone, well you know what "diure" is, so
what is anti-diuretic? Anti-diuretic is going to be a hormone that holds on to fluids inside
our body. Where is that going to go? It's going to go to our kidney because our kidney
is in control of osmoregulation. What's the next one. The next one as we work our way
down is going to be the thyroid. So we're going to move all the way down here this would
be the thyroid gland. It sits right in here. Basically it does two things that are important.
It gives off what are called T3 and T4. Those hormones and the numbers relate to the number
of iodine atoms that are found within it. And so basically maybe you've heard of a goiter,
when you get an inflamed thyroid. Basically what our thyroid does is it regulates metabolism.
And so it's going to give off these two chemicals T3 and T4 and that's going to speed up metabolism
inside our body. And so if you have a hyperactive thyroid you have high metabolism. If you have
an inactive thyroid then you're going to have really slow metabolism. And so basically it's
control of that. And the other thing that it does is it secretes something called calcitonin.
And again endocrine system's really important in feedback loops. And so the calcium that
we have in our blood, the level that we have is super important. Especially in nerves and
in muscle firing. If we don't have the correct amount of blood calcium, we're going to die.
And so basically what the thyroid does, is that when you secrete the thyroid, it's going
to lower the calcium. Where's the calcium going to go? It's going to go back into the,
we're going to secrete some through the kidneys, but it's going to go back into the bones.
And so there's another hormone that kind of goes with that and so this looks like a butterfly,
but there are going to be these tiny little hormones in here called the parathyroid. They
sit right within the thyroid. And their going to secrete something called parathyroid hormone.
What does that do? Well, if the blood calcium level goes too low, it's going to raise the
blood calcium. And so these two, the thyroid and the parathyroid are going to work together
to basically keep the blood calcium level correct. It's the same way that insulin and
glucagon work in the pancreas. Speaking of which, let's go to the next one. And so the
pancreas is kind of hard to see in this diagram. But the pancreas is going to sit right here,
it's again behind the stomach and it's going to empty right here into the duodenum. So
it's going to empty enzymes in here, but it's also on its surface it's got beta and alpha
cells that are going to secrete insulin and glucagon. Insulin is going to be secreted
if we ever need to lower the blood sugar and glucagon if we ever need to raise the blood
sugar. So basically what insulin does is when it's secreted it allows our cells to take
in that blood sugar, that glucose. And glucagon, when we release that it's going to release
more of that insulin form the glycogen that's found right here in the liver. So that's the
pancreas. On the top of our kidneys, so these would be our kidneys right here, on the top
of them we have our adrenal glands. The adrenal glands have two parts to it. The adrenal cortex
is going to be on the outside. The adrenal cortex is basically what it does is secretes
glucocorticoids. And so if you ever have an injury and you get huge amounts of inflammation
in it, they secrete anti-inflammatories. And so if you've ever taken an anti-inflammatory,
an example would be like Advil, basically the glucocorticoids are going to do the same
thing. They don't need to act right away, and so these are actually connected by hormones
to the pituitary so the message can come from the brain, we have an injury down to the pituitary
and eventually to the adrenal cortex. But that's not what you're familiar with in the
adrenal gland. You're familiar with adrenaline. So there's a nervous connection from the brain,
all the way down here to the center of the adrenal gland. That's called the adrenal medulla.
Basically what it's going to have it do, it's going to secrete epinephrine. Epinephrine
is adrenaline. It's going to go throughout your body and it's going to trigger that fight
or flight response. And so again, if you almost get into a car accident, nervous system is
going to allow you to kind of not get in that car accident, but after that you're going
to feel this adrenaline coursing through your body. Your metabolism is going to speed up.
You're to suppress like your digestive system. You're going to become more alert. And that's
all a result of the adrenal medulla. Next we've got, down at the bottom, we just have
the sex hormones and the sex glands. We've go the ovaries, and so this would be in females,
and then the testes if we're talking about males. Ovaries are going to give off estrogen.
Testes are going to give off testosterone among other things. But basically those are
responsible for your female and male sex characteristics. Now when you go through puberty, before you
go through puberty they're not really cranking out a lot of estrogen and testosterone. But
once you go through puberty, they're getting a signal from the pituitary gland that says
now it's time to make these sex hormones and then we get those secondary sex characteristics.
Okay, so how did you do? Can you remember the ten glands? Can you remember the hormones
that they secreted? And what they did? Well, let's try. Okay. So as we go through this
. . . Testes - Where are they found? They're found right down here. What do they do? They
give off . . . testosterone, that's right. What about the ovaries? Where are they found?
Ovaries are going to be found right here. What do they give off . . . estrogen, that's
right. Sorry for the awkward pauses. It's like Dora the Explorer. Next we've got the
adrenal medulla. Where's that found? Yeah, that's the green. What do they give off . . . that's
right, epinephrine. Let's got to the next one, adrenal cortex. Where is that? It's going
to be the yellow part remember around the adrenal gland. What do they give off? I bet
you've forgotten this, those are glucocorticoids. They're going to be anti-inflammatories. What's
next? That's going to be the pancreas. Pancreas is found right here. What's it give off . . . insulin,
glucagon. Those regulate blood sugar. Let's go to the next one. It's the parathyroid.
That's right, that's going to be within the thyroid. They used to actually when people
get goiters, they cut parts of the thyroid out and then person would immediately die
because they didn't understand what the parathyroid did. So a parathyroid is going to be inside
here. What's it going to secrete . . . parathyroid hormone, that's right. And that's going to
raise blood calcium. Right above that we've got the thyroid. Thyroid is going to give
off two things. Can you remember those . . . It's going to give off calcitonin, that's going
to lower blood calcium and it's also going to give off T3 and T4. Okay. Let's go to the
next one. Posterior pituitary. So that's going to be way up here. What does that give off
. . . anti-diuretic hormone. That's right. That's going to keep our body holding on to
water, retaining water. And then we've got the anterior pituitary in the front. That
gives off a lot of things. Do you remember what it gives off . . . thinking back to Robert
Wadlow . . . right, it gives off growth hormone. That's going to cause our cells to grow. And
finally we've got the pineal gland. Pineal gland, close your eyes, you're going to start
secreting . . . melatonin, that's right. And that allows us to sync up our circadian rhythms.
So these are the top 10 glands, top 10 hormones and I hope that's all helpful.